The present disclosure relates to a communication apparatus and a communication system which execute a communication process in accordance with a communication protocol such as SIP (Session Initiation Protocol).
In recent years, for example, SIP (Session Initiation Protocol) is known as a communication protocol in performing a communication process via a communication network such as the Internet and an intranet. SIP is a signaling protocol for an application layer which is defined in RFC 3261. For example, SIP is used for communication processes such as IP-FAX (facsimile), IP phone, video phone, video conferencing, video chat, and instant messenger.
Meanwhile, a technology is known in which, in the case where a reception-side communication apparatus is in an non-executable state when a communication process is executed using SIP, a transmission-side communication apparatus executes the communication process again after elapse of a retry time period received from the reception-side communication apparatus. With this technology, a useless communication process with the reception-side communication apparatus in the non-executable state as a destination is suppressed. It should be noted that examples of the non-executable state include memory fullness, a paper out state, paper jam, and a busy state.